add UUID as new entry value in the add_entries processor

[Zhangxunmt]

Description

Added a new entry in the add_entries processor that generates a unique ID for each record. This is needed for cases where the original source data does not contain a unique identifier. The unique ID is essential for running asynchronous batch inference jobs, as it is used to match and merge the inference results back with the source data.

UUID.randomUUID() (UUID v4) uses Java's SecureRandom, and collision probability is so low it has never been observed in practice in any production system, which is what all major distributed systems use for this exact problem.

Usage

  processor:
    - add_entries:
        entries:
          - key: recordId
            value_expression: 'generateUuid()'

Issues Resolved

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
• New functionality has a documentation issue. Please link to it in this PR.
  • New functionality has javadoc added
• Commits are signed with a real name per the DCO

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[graytaylor0]

This may be better implemented as an expression function rather than a new parameter

  processor:
    - add_entries:
        entries:
          - key: recordId
            value_expression: 'generate_uuid()'

[Zhangxunmt]

This may be better implemented as an expression function rather than a new parameter

  processor:
    - add_entries:
        entries:
          - key: recordId
            value_expression: 'generate_uuid()'

Thanks for the comment! @graytaylor0 Make sense to use a function. BTW, I think the data prepper documents needs update to list common available functions. Probably I can do that in a separate PR.

[graytaylor0]

Looks good! Please follow up with a documentation change (https://docs.opensearch.org/latest/data-prepper/pipelines/functions/). Thanks!

[Zhangxunmt]

Looks good! Please follow up with a documentation change (https://docs.opensearch.org/latest/data-prepper/pipelines/functions/). Thanks!

Docs update PR -> opensearch-project/documentation-website#12130.

[dlvenable]

Thanks @Zhangxunmt for this contribution! I just have a couple comments.

[dlvenable]

Data Prepper functions use lowerCamelCase. Please update to generateUuid.

Suggested change

	static final String FUNCTION_NAME = "generate_uuid";
	static final String FUNCTION_NAME = "generateUuid";

[Zhangxunmt]

Good catch!

[dlvenable]

This would be clearer and be retained in code rather than as a comment.

UUID regeneratedUuid = 
  assertDoesNotThrow(() -> UUID.fromString("hello"));
assertThat(regeneratedUuid.toString(), equalTo(uuidStr));

[dlvenable]

Be sure to update these as well.

[dlvenable]

Thanks @Zhangxunmt !